Process for providing asbestos-cement pipes with sockets



April 24, 1962 G. MARCHIOLI ETAL PROCESS FOR PROVIDING ASBESTOSCEMENTPIPES WITH SOCKETS 4 Sheets-Sheet 1 Filed Sept. 50, 1959 p i 1962 G.MARCHIOLI ETAL 3,031,365 PROCESS FOR PROVIDING ASBESTOS-CEMENT PIPESWITH SOCKETS Filed Sept. 30, 1959 4 Sheets-Sheet 2 April 24, 1962 G.MARCHIOLI ETAL PROCESS FOR PROVIDING ASBESTOS-CEMENT PIPES WITH SOCKETS4 Sheets-Sheet 3 Filed Sept. 30, 1959 A ril 24, 1962 G. MARCHIOLI ETAL3,031,365

PROCESS FOR PROVIDING ASBESTOS-CEMENT PIPES WITH SOCKETS Filed Sept. 50,1959 4 Sheets-Sheet 4 United States atent PROCESS FOR PROVIDINGASBESTOS-CEMENT PIPES WITH SOCKETS Giorgio Marchioli and GiuseppeGremigni, Milan, Italy;

Various ways have been previously proposed for applying sockets toasbestos-cement pipes. For example, it is known to apply a preformedasbestos-cement socket in the fresh state to a pipe which is also in thefresh state, in order to obtain, after hardening of the cement, anadhesion between the socket and pipe.

With the above known method however it is necessary that deformation ofeither the fresh pipe or the fresh socket be confined within very narrowlimits, because the material which is moist, but which contains acomparatively small proportion of water and is strongly rammed orcompressed, can not stand considerable deformations Without beingspoiled. Hence, it has been further proposed not to deform the externalsurface of the two parts to be joined, but to limit the deformation tomere variation of volume as caused by the compression of one elementupon the other one.

As distinguished from the above, the process embodying the presentinvention initially modifies the material forming the socket and thepipe end in such a manner as to render it capable of standing evenconsiderable deformations and, therefore, there is no need to observethe previously imposed limitations on deformation of the material, withthe further advantage that the union of the material constituting thesocket with that constituting the pipe is realized in a much morecomplete and perfect manner.

According to the present invention the end of the previously shapedgreen uncured asbestos-cement pipe is wetted to such extent as to softenit by absorption of water; the material forming wholly or partly thesocket, is applied to the softened pipe end; and the two parts arejoined together in a stable manner by application of radial compressionagainst one another while excess water is simultaneously removedtherefrom.

More particularly the above method is preferably carried out by wettingone end of the fresh pipe introducing thereinto part of a resilient,radially expansible inflatable core, applying to the remaining part ofthe core the material destined to form the socket, introducing the wholeinto a foraminous cover within a permeable mould and inflating the coreto obtain radial compression and elimination of excess water.

The above, and other features and advantages of the invention, will beapparent in the following detailed description of an illustrativeembodiment thereof which is to be read in connection with theaccompanying drawings, wherein:

FIGS. 1 to 7 are diagrammatic views illustrating successive steps in theprocess embodying this invention;

FIG. 8 is a transverse sectional view of an apparatus suitable for usein practicing the process;

FIG. 9 is a longitudinal sectional view of the apparatus of FIG. 8; and

FIG. is a view illustrating an alternative procedure for providing thematerial of which the socket is formed at one end of a pipe.

Referring to the drawings in detail, and initially to FIG. 1, there isshown a fresh pipe 1, that is, a previously shaped and compressed greenuncured pipe, from which all excess water has already been removed; andwhich is mounted on a rigid mandrel 2. The end portion of the pipe 1 isfirst chamfered by removal of material or by deformation as indicated at3 in FIG. 2; then the pipe is displaced axially with respect to themandrel in such a way as to make the chamfered end project beyond themandrel and a water jet '4 is directed thereunto as indicateddiagrammatically in FIG. 3. The chamfered end 3 then is flared, forinstance by using a tool of round shape of the kind indicated at 5 inFIG. 4.

Referring now to FIG. 5, there is shown an inflatable core 6, carried byany suitable support 7, and comprising two coaxial cylindrical parts ofdifferent diameters. A ring 8 of material equal to that of which thepipe 1 is made, is applied or shaped on the part of core 6 of largerdiameter, said ring having a border 9 which is chamfered externally. Thering 8 placed upon the core 6 is wetted by a water jet 10 in such a waythat it too becomes soaked with water and softened.

Then the support 7 and the mandrel 2 are moved relatively toward eachother so that the narrower part of the core 6 enters into the pipe 1 andthe chamfered end or border 9 of the ring 8 penetrates into and comesinto surface contact with the flared end 3 of the pipe 1, as shown inFIG. 6.

Around the assembly as above described, there are closed the partsconstituting a permeable mould 11 which defines the shape that theoutside of the finished pipe is to assume at the socket end.

The core 6 then is inflated to exert a radially outward pressure uponthe inner wall surface of the end of the pipe 1 and of the ring 8 whileejecting the excess water contained therein through the permeable wallof the mould 11, whereby the two parts 3 and 8 become joined together toform a single and homogeneous piece. The finished pipe is then extractedfrom the open mould, while pulling out the deflated core, as indicatedin FIG. 7.

In a practical apparatus (FIGS. 8 and 9) for practicing the aboveprocess, the core 6 made for instance of rubber is mounted on a rigidpiece 12 and is blocked, at its ends,

by two terminal rings 13 and 14. The piece 12 is hollow axially, as at15, and is provided with radial channels 16 so that, by introducing airor water under pressure through the connection 17 at one end, it ispossible to inflate the core, which thereby can expand radially but notaxially.

When the pipe 1 and ring 8 are joined in the apparatus of FIGS. 8 and 9,a thin metal wire gauze or a thin perforated metal sheet 21 or otherwater permeable sheet material is placed thereover prior to closing theparts 11 of the mould, and the latter are perforated with holes 18 fordischarging of the excess water. The parts 11 of the mould are supportedfor radial displacement in a ring 19 by means of hydraulic jacks 20 orany other convenient means.

The process according to the invention is susceptible of variations fromthe specific embodiment hereinbefore described. For instance the ring 8may be applied wholly externally with respect to the pipe 1 and, in thatcase, the flare at the end 3 of the pipe 1 is made less sharp or ifdesired may even be dispensed with.

The material for obtaining the socket may even not constitute a ringseparate from the pipe 1. For instance thanks to the softened state ofthe wetted pipe 1, it is possible to make an axial cut at its end 3 sothat, on introducing the core 6 into the end 3 of the pipe, the cutwidens to form the recess 22 shown in FIG. 10. Then, in said recessthere is applied a piece 23- of equal dimensions made of the samematerial and the whole is shaped in the mould in the same manner asabove described. Of course, the end 3 of pipe 1 may be provided withmore than one of the cuts and the corresponding pieces 23 to define thematerial for forming the socket end.

Although an illustrative embodiment of the invention and specificmodifications thereof have been described in detail herein withreference to the accompanying drawings, it is to be understood that theinvention is not limited to that precise embodiment or the modificationsthereof,

.and that various other changes and further modifications may beeffected therein by one skilled in the art without departing from thescope or spirit of the invention except as defined in the appendedclaim.

We claim:

A process for forming a bell-end socket on an asbestoscement pipecomprising wetting the end of a green uncured asbestos-cement pipe so asto soften the same, inserting a resilient, inflatable core member intosaid softened end of the pipe, placing additional socket formingasbestos-cement material on said core member, surrounding said end ofthe pipe and said additional socket forming material with a foraminouscover, inserting said end of the pipe and said additional socket formingmaterial surrounded by the foraminous cover in a perforated mould, andinflating said core member so that the latter expands radially andexerts a uniform radial compression of said end of the pipe and saidadditional socket forming material against said mould While the excessmoisture is simultaneously expressed through said foraminous cover andperforated mould.

References Cited in the file of this patent UNITED STATES PATENTS693,571 Shaw Feb. 18, 1902 1,285,546 Young Nov. 19, 1918 2,383,582Barbehenn Aug. 28, 1945 2,528,155 Magnani Oct. 31, 1950 2,962,408Fourmanoit Nov. 29, 1960

